How to generate random variable names in C++ using macros?

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Try the following:

// One level of macro indirection is required in order to resolve __COUNTER__,
// and get varname1 instead of varname__COUNTER__.
#define CONCAT(a, b) CONCAT_INNER(a, b)
#define CONCAT_INNER(a, b) a ## b

#define UNIQUE_NAME(base) CONCAT(base, __COUNTER__)

void main() {
  int UNIQUE_NAME(foo) = 123;  // int foo0 = 123;
  std::cout << foo0;           // prints "123"
}

__COUNTER__ may have portability issues. If this is a problem, you can use __LINE__ instead and as long as you aren’t calling the macro more than once per line or sharing the names across compilation units, you will be just fine.

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